EGFR and metastatic colorectal cancer: Despite preclinical data strongly supported a potential role of HER3 signaling in acquired resistance to HER1 inhibitors [56], two randomized phase II study in HNSCC [53] and metastatic colorectal cancers [57] showed no benefits of the dual inhibition of HER1 and HER3 with duligotuzumab as compared to inhibition of HER1 alone with cetuximab.